The present invention relates to a navigation device which performs a 3 dimensional display.
FIG. 16 is a block diagram of a conventional navigation device. In the figure, 110 is a CPU (central processing unit) which performs various types of calculations. The CPU controls the vehicle position detection means 110A which detects the vehicle position on the basis of signals from a sensor or a GPS receiver, a route searching means 110B which searches a route to a destination from a detected vehicle position and a display conversion means 110C which converts route data read from a CD-ROM to bird""s eye view data from a fixed viewpoint. 111 is a ROM (read on memory) which stores a program for various calculations performed by the CPU 110, 112 is a memory (DRAM) which stores calculation results and the like from the CPU 110 or data from a bearing sensor, distance sensor, GPS receiver, CDROM driver or the like. 113 is a backup memory (SRAM for preserving necessary data in the event of a power supply termination to the main device. 114 is a memory (Chinese characters, font ROM) which stores patterns such as signs or letters for display on the crystal display. 115 is an image processor for forming a display image based on map data or the vehicle present position. 116 is a memory (VRAM) which composes map data output from the CPU 110, present position data and Chinese characters, town names output from the font ROM 114 and fonts and Chinese characters for road names or the like and stores images displayed on the crystal display. 117 is a RGB conversion circuit for converting output data from the VRAM 116 to color data. The color signals are output from the RGB conversion circuit 117 to the crystal display. 118 is a communication interface.
The operation of the invention will be explained next.
FIG. 17 is a flowchart showing the operation of a conventional navigation device.
In a step ST1601, a display angle xcex8x of the bird""s eye view map which displays the distance from the vehicle position to the intersection. In a step ST1602, a bearing is determined from road network data read from a CD-ROM and the vehicle position. Conversion is performed to a bird""s eye view map at the angle xcex8x calculated in a step ST1601 and an enlarged screen is prepared so that the direction of progress is in an upward direction. In a step ST1603, it is determined whether an intersection has been reached and in the event that the intersection has been reached, the routine is terminated.
Steps ST1601, 1602, 1603 are repeated as shown in FIG. 17 until an intersection is reached from a current vehicle position. The angle xcex8x approaches 0 as the vehicle position approaches the intersection. When the vehicle position is distant from the target intersection, the viewpoint is low, and as shown in FIG. 18(a), the display range is wide. However as the vehicle approaches the target intersection, the viewpoint rises, and as shown in FIG. 18(b), the display range narrows to express the distance in an easily understandable form. Furthermore when the vehicle position has almost reached the intersection, the viewpoint is roughly above the target intersection and becomes a bird""s eye view map as shown in FIG. 18(c).
As the conventional navigation device is constructed as above, the display range narrows as the intersection is reached. For example, when the difference between direction in which the vehicle is travelling and the direction to the position of the intersection is great, the problem has arisen that it has not been possible to display the intersection.
The present invention is proposed to solve the above problems and has the object of providing a navigation device which can display an intersection even when there is a great difference the direction in which the vehicle is travelling and the direction to the position of the intersection.
The navigation device of the present invention is a navigation device which performs a 3 dimensional display when approaching an intersection. The navigation device comprises a direction of travel detection means which detects the direction-of-travel of the vehicle, a direction-to-intersection detection means which calculates the difference between the direction of travel of the vehicle and the direction to the position of the intersection, a viewpoint direction calculation means which detects the direction of the viewpoint in order to perform 3 dimensional display based on the difference between a detected direction of vehicle travel and a calculated direction, and a display means which performs display based on a calculated viewpoint direction.
As a result of this arrangement, even when the difference between the direction in which the vehicle is travelling and the direction to the position of the intersection is great, it is possible display the intersection.
The navigation device of the present invention is a navigation device which performs a 3 dimensional display when approaching an intersection. The navigation device comprises a vehicle position detection means which detects a vehicle position, an intersection distance calculation means which calculates a distance from a detected vehicle position to an intersection, a viewpoint position calculation means which calculates the height of the viewpoint so that the height of the viewpoint for the purposes of 3 dimensional display is reduced as the distance from the calculated vehicle position to the intersection is reduced, and a display means which carries out a display based on the calculated viewpoint height.
As a result of the above arrangement, it is possible to create a more realistic appearance of approaching the intersection.
The navigation device according to the present invention is adapted to perform three dimensional display on approaching an intersection. The navigation device is provided with a traffic signal disposition means which disposes a traffic signal at a position which is close to an actual position on an intersection when an intersection is determined to exist in a direction of vehicle travel, and a display means which displays a traffic signal on a disposed position.
The navigation device of the present invention is a navigation device which performs a 3 dimensional display when approaching an intersection. The device comprises a road existence determination means which determines whether or not a road exists on the left side as seen from the direction in which the vehicle is travelling at the intersection, a signal mechanism disposal means which disposes a signal mechanism at a position facing the direction of right turn in the road in the vicinity of the intersection when a road is determined to exist, and which disposes a signal mechanism at a position facing the direction of left turn in the road in the direction in which the vehicle is travelling in the vicinity of the intersection when a road is determined to not exist, and a display means which carries out a display which disposes a signal mechanism at a disposed position.
As a result of the arrangement above, it is possible to perform a 3 dimensional display at the intersection in a realistic form.
The navigation device of the present invention is a navigation device which performs a 3 dimensional display when approaching an intersection. It comprises a signal generation means which a right-hand or a left-hand signal at the intersection when the vehicle approaches an intersection which turns left or right, a road width correction means which corrects a road width of roads crossing intersections other than the target intersection when the vehicle approaches a right or left turning intersection, a display means which displays a generated signal on an intersection and which displays intersections other than the target intersection with a corrected width.
By the above arrangement, it is possible to recognize a right or left turning intersection without errors.